The Lutheran (Lu) blood group and basal cell adhesion molecule (BCAM) antigens are both carried by 2 glycoprotein isoforms of the immunoglobulin superfamily representing receptors for the laminin alpha(5) chain. It is a transmembrane receptor with five immunoglobulin-like domains in its extracellular region , and is therefore classified as a member of the immunoglobulin (Ig) gene family. In addition to red blood cells , Lu/BCAM proteins are expressed in endothelial cells of vascular capillaries and in epithelial cells of several tissues. BCAM/LU has a wide tissue distribution with a predominant expression in the basal layer of the epithelium and the endothelium of blood vessel walls. As designated as CD239 recently , BCAM and LU share a significant sequence similarity with the CD146 (MUC18) and CD166 , and themselves are adhesion molecules that bind laminin with high affinity. Laminins are found in all basement membranes and are involved in cell differentiation , adhesion , migration , and proliferation. BCAM is upregulated following malignant transformation of some cell types in vivo and in vitro , thus being a candidate molecule involved in tumor progression. In addition , BCAM interacts with integrin in sickle red cells , and thus may potentially play a role in vaso-occlusive episodes.
